nimbus-eth2/beacon_chain/consensus_object_pools/sync_committee_msg_pool.nim

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# beacon_chain
# Copyright (c) 2018-2024 Status Research & Development GmbH
# Licensed and distributed under either of
# * MIT license (license terms in the root directory or at https://opensource.org/licenses/MIT).
# * Apache v2 license (license terms in the root directory or at https://www.apache.org/licenses/LICENSE-2.0).
# at your option. This file may not be copied, modified, or distributed except according to those terms.
{.push raises: [].}
import
std/[algorithm, sequtils, sets, tables],
stew/shims/hashes,
eth/p2p/discoveryv5/random2,
chronicles,
../spec/[crypto, digest, forks],
../spec/datatypes/altair
export hashes, sets, tables, altair
logScope:
topics = "syncpool"
const
syncCommitteeMsgsRetentionSlots = 3
## How many slots to retain sync committee
## messsages before discarding them.
type
SyncCommitteeMsgKey = object
originator: uint64 # ValidatorIndex to avoid invalid values
slot: Slot
subcommitteeIdx: uint64 # SyncSubcommitteeIndex to avoid invalid values
TrustedSyncCommitteeMsg* = object
subcommitteeIdx*: SyncSubcommitteeIndex
positionInCommittee*: uint64
signature*: CookedSig
BestSyncSubcommitteeContribution* = object
totalParticipants*: int
participationBits*: SyncCommitteeAggregationBits
signature*: CookedSig
BestSyncSubcommitteeContributions* = object
subnets*: array[SYNC_COMMITTEE_SUBNET_COUNT,
BestSyncSubcommitteeContribution]
OnSyncContributionCallback* =
proc(data: SignedContributionAndProof) {.gcsafe, raises: [].}
# Messages from different slots / forks may sign the same beacon block root.
# Messages across slots are compatible, but not across forks (signing root).
# Messages from different periods have different signers, so are incompatible.
# Note that the sync committee is determined by `message.slot + 1`, the fork
# is determined by `message.slot`, and both can be different from `bid.slot`.
SyncMsgTarget = object
bid: BlockId # Based on message `beacon_block_root`
period: SyncCommitteePeriod # Based on message `slot + 1`
fork: ConsensusFork # Based on message `slot`
SyncCommitteeMsgPool* = object
seenSyncMsgByAuthor*: Table[SyncCommitteeMsgKey, Eth2Digest]
seenContributionByAuthor*: HashSet[SyncCommitteeMsgKey]
syncMessages*: Table[SyncMsgTarget, seq[TrustedSyncCommitteeMsg]]
bestContributions*: Table[SyncMsgTarget, BestSyncSubcommitteeContributions]
onContributionReceived*: OnSyncContributionCallback
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rng: ref HmacDrbgContext
cfg: RuntimeConfig
func hash*(x: SyncCommitteeMsgKey): Hash =
hashAllFields(x)
func toSyncMsgTarget(
cfg: RuntimeConfig, bid: BlockId, slot: Slot): SyncMsgTarget =
SyncMsgTarget(
bid: bid,
period: (slot + 1).sync_committee_period,
fork: cfg.consensusForkAtEpoch(slot.epoch))
func hash(x: SyncMsgTarget): Hash =
hashAllFields(x)
func `<`(x, y: SyncMsgTarget): bool =
if x.bid.slot != y.bid.slot:
x.bid.slot < y.bid.slot
elif x.period != y.period:
x.period < y.period
else:
x.fork < y.fork
func init*(T: type SyncCommitteeMsgPool,
2022-06-21 08:29:16 +00:00
rng: ref HmacDrbgContext,
cfg: RuntimeConfig,
onSyncContribution: OnSyncContributionCallback = nil
): SyncCommitteeMsgPool =
T(rng: rng, cfg: cfg, onContributionReceived: onSyncContribution)
func pruneData*(pool: var SyncCommitteeMsgPool, slot: Slot, force = false) =
## This should be called at the end of slot.
clear pool.seenContributionByAuthor
clear pool.seenSyncMsgByAuthor
if slot < syncCommitteeMsgsRetentionSlots:
return
# Messages signing a `beacon_block_root` may remain valid over multiple slots.
# Therefore, we filter by the targeted `BlockId` instead of message `slot`.
let
minSlotToRetain = slot - syncCommitteeMsgsRetentionSlots
minEntriesToKeep = if force: 0 else: syncCommitteeMsgsRetentionSlots
template pruneTable(table: untyped) =
if table.len > minEntriesToKeep:
var targets = table.keys().toSeq()
targets.sort(order = SortOrder.Descending)
for i in minEntriesToKeep ..< targets.len:
if targets[i].bid.slot < minSlotToRetain:
table.del targets[i]
pruneTable pool.syncMessages
pruneTable pool.bestContributions
func isSeen*(
pool: SyncCommitteeMsgPool,
msg: SyncCommitteeMessage,
subcommitteeIdx: SyncSubcommitteeIndex,
headBid: BlockId): bool =
let seenKey = SyncCommitteeMsgKey(
originator: msg.validator_index, # Might be unvalidated at this point
slot: msg.slot,
subcommitteeIdx: subcommitteeIdx.uint64)
return
if seenKey notin pool.seenSyncMsgByAuthor:
false
elif msg.beacon_block_root == headBid.root:
pool.seenSyncMsgByAuthor.getOrDefault(seenKey) == headBid.root
else:
true
proc addSyncCommitteeMessage*(
pool: var SyncCommitteeMsgPool,
slot: Slot,
bid: BlockId,
validatorIndex: uint64,
signature: CookedSig,
subcommitteeIdx: SyncSubcommitteeIndex,
positionsInCommittee: seq[uint64]) =
let seenKey = SyncCommitteeMsgKey(
originator: validatorIndex,
slot: slot,
subcommitteeIdx: subcommitteeIdx.uint64)
pool.seenSyncMsgByAuthor[seenKey] = bid.root
func registerVotes(votes: var seq[TrustedSyncCommitteeMsg]) =
for position in positionsInCommittee:
block addVote:
for vote in votes:
if vote.subcommitteeIdx == subcommitteeIdx and
vote.positionInCommittee == position:
break addVote
votes.add TrustedSyncCommitteeMsg(
subcommitteeIdx: subcommitteeIdx,
positionInCommittee: position,
signature: signature)
let target = pool.cfg.toSyncMsgTarget(bid, slot)
pool.syncMessages.mgetOrPut(target, @[]).registerVotes()
debug "Sync committee message resolved",
slot = slot, blockRoot = shortLog(target.bid.root), validatorIndex
func computeAggregateSig(votes: seq[TrustedSyncCommitteeMsg],
subcommitteeIdx: SyncSubcommitteeIndex,
contribution: var SyncCommitteeContribution): bool =
var
aggregateSig {.noinit.}: AggregateSignature
initialized = false
contribution.aggregation_bits.reset()
for vote in votes:
if vote.subcommitteeIdx != subcommitteeIdx:
continue
if not contribution.aggregation_bits[vote.positionInCommittee]:
if not initialized:
initialized = true
aggregateSig.init(vote.signature)
else:
aggregateSig.aggregate(vote.signature)
contribution.aggregation_bits.setBit vote.positionInCommittee
if initialized:
contribution.signature = aggregateSig.finish.toValidatorSig
else:
contribution.signature = ValidatorSig.infinity
initialized
func produceContribution*(
pool: SyncCommitteeMsgPool,
slot: Slot,
headBid: BlockId,
subcommitteeIdx: SyncSubcommitteeIndex,
outContribution: var SyncCommitteeContribution): bool =
let target = pool.cfg.toSyncMsgTarget(headBid, slot)
if target in pool.syncMessages:
outContribution.slot = slot
outContribution.beacon_block_root = headBid.root
outContribution.subcommittee_index = subcommitteeIdx.asUInt64
try:
computeAggregateSig(pool.syncMessages[target],
subcommitteeIdx,
outContribution)
except KeyError:
raiseAssert "We have checked for the key upfront"
else:
false
func addAggregateAux(bestVotes: var BestSyncSubcommitteeContributions,
contribution: SyncCommitteeContribution) =
let
currentBestTotalParticipants =
bestVotes.subnets[contribution.subcommittee_index].totalParticipants
newBestTotalParticipants = countOnes(contribution.aggregation_bits)
if newBestTotalParticipants > currentBestTotalParticipants:
bestVotes.subnets[contribution.subcommittee_index] =
BestSyncSubcommitteeContribution(
totalParticipants: newBestTotalParticipants,
participationBits: contribution.aggregation_bits,
signature: contribution.signature.load.get)
func isSeen*(
pool: SyncCommitteeMsgPool,
msg: ContributionAndProof): bool =
let seenKey = SyncCommitteeMsgKey(
originator: msg.aggregator_index,
slot: msg.contribution.slot,
subcommitteeIdx: msg.contribution.subcommittee_index)
seenKey in pool.seenContributionByAuthor
func covers(
bestVotes: BestSyncSubcommitteeContributions,
contribution: SyncCommitteeContribution): bool =
contribution.aggregation_bits.isSubsetOf(
bestVotes.subnets[contribution.subcommittee_index].participationBits)
func covers*(
pool: var SyncCommitteeMsgPool,
contribution: SyncCommitteeContribution,
bid: BlockId): bool =
## Return true iff the given contribution brings no new information compared
## to the contributions already seen in the pool, ie if the contriubution is a
## subset of the best contribution so far
let target = pool.cfg.toSyncMsgTarget(bid, contribution.slot)
pool.bestContributions.withValue(target, best):
return best[].covers(contribution)
return false
proc addContribution(pool: var SyncCommitteeMsgPool,
aggregator_index: uint64,
contribution: SyncCommitteeContribution,
bid: BlockId,
signature: CookedSig) =
let seenKey = SyncCommitteeMsgKey(
originator: aggregator_index,
slot: contribution.slot,
subcommitteeIdx: contribution.subcommittee_index)
pool.seenContributionByAuthor.incl seenKey
let target = pool.cfg.toSyncMsgTarget(bid, contribution.slot)
if target notin pool.bestContributions:
let totalParticipants = countOnes(contribution.aggregation_bits)
var initialBestContributions = BestSyncSubcommitteeContributions()
initialBestContributions.subnets[contribution.subcommittee_index] =
BestSyncSubcommitteeContribution(
totalParticipants: totalParticipants,
participationBits: contribution.aggregation_bits,
signature: signature)
pool.bestContributions[target] = initialBestContributions
else:
try:
addAggregateAux(pool.bestContributions[target], contribution)
except KeyError:
raiseAssert "We have checked for the key upfront"
proc addContribution*(pool: var SyncCommitteeMsgPool,
scproof: SignedContributionAndProof,
bid: BlockId,
signature: CookedSig) =
pool.addContribution(
scproof.message.aggregator_index,
scproof.message.contribution,
bid, signature)
if not(isNil(pool.onContributionReceived)):
pool.onContributionReceived(scproof)
proc produceSyncAggregateAux(
contributions: BestSyncSubcommitteeContributions): SyncAggregate =
var
aggregateSig {.noinit.}: AggregateSignature
initialized = false
startTime = Moment.now
aggregate: SyncAggregate
for subcommitteeIdx in SyncSubcommitteeIndex:
if contributions.subnets[subcommitteeIdx].totalParticipants == 0:
continue
for pos, value in contributions.subnets[subcommitteeIdx].participationBits:
if value:
let globalPos = subcommitteeIdx.asInt * SYNC_SUBCOMMITTEE_SIZE + pos
aggregate.sync_committee_bits.setBit globalPos
if not initialized:
initialized = true
aggregateSig.init(contributions.subnets[subcommitteeIdx].signature)
else:
aggregateSig.aggregate(contributions.subnets[subcommitteeIdx].signature)
if initialized:
aggregate.sync_committee_signature = aggregateSig.finish.toValidatorSig
else:
aggregate.sync_committee_signature = ValidatorSig.infinity
let duration = Moment.now - startTime
debug "SyncAggregate produced", duration,
bits = aggregate.sync_committee_bits
aggregate
proc produceSyncAggregate*(
pool: SyncCommitteeMsgPool,
bid: BlockId,
signatureSlot: Slot): SyncAggregate =
# Sync committee signs previous slot, relative to when new block is produced
let target = pool.cfg.toSyncMsgTarget(bid, max(signatureSlot, 1.Slot) - 1)
if target in pool.bestContributions:
try:
produceSyncAggregateAux(pool.bestContributions[target])
except KeyError:
raiseAssert "We have checked for the key upfront"
else:
SyncAggregate.init()
proc isEpochLeadTime*(
pool: SyncCommitteeMsgPool, epochsToSyncPeriod: uint64): bool =
# https://github.com/ethereum/consensus-specs/blob/v1.4.0/specs/altair/validator.md#sync-committee-subnet-stability
# This ensures a uniform distribution without requiring additional state:
# (1/4) = 1/4, 4 slots out
# (3/4) * (1/3) = 1/4, 3 slots out
# (3/4) * (2/3) * (1/2) = 1/4, 2 slots out
# (3/4) * (2/3) * (1/2) * (1/1) = 1/4, 1 slot out
doAssert epochsToSyncPeriod > 0
epochsToSyncPeriod == 1 or pool.rng[].rand(epochsToSyncPeriod - 1) == 0